The present invention relates to a robot apparatus particularly adapted for removing and handling die cast parts and more particularly to an extractor arm for handling die cast parts.
A die cast machine includes a mold and an inlet port for injecting molten moldable material into the mold. A die cast article is formed by closing the mold, injecting the molten material through the inlet port into the mold, allowing the material to solidify, opening the mold, and removing the molded article. The relatively hot, and often heavy, molded article typically is mechanically removed from the mold and delivered to the next processing machine, for example a trim press, for further processing of the article. If removed manually, a danger or hazard to the worker exists. Therefore, mechanical devices have been used to some extent. Several known devices for extracting the die cast articles from the die cast machine are "robot-like" devices to repetitively perform the rote, mechanical activity of removing the articles from the die cast machine and delivering the articles to the next processing station.
However, known extractor devices are not without their drawbacks. A first known extractor device includes a claw, a telescoping arm supporting the claw, and a support structure pivotally supporting the telescoping arm for movement in a substantially vertical plane. Control of the vertical claw position is difficult because the claw can be vertically positioned only by pivoting the arm at the support means. Because the claw is typically located remotely (for example 2 to 15 feet) from the pivot, slight errors in the angular orientation of the arm result in large errors in the vertical position of the claw. Further, devices having single linear motion have problems with long strokes bearing weight at the end of the arm. In addition, in the isolated case wherein the arm is positioned horizontally, the claw cannot be moved in a horizontal plane as is desirable to cleanly remove the die cast article from the die cast machine.
A second known extractor device includes a claw, an arm supporting the claw, and a support structure supporting the arm. The arm includes three pivotal interconnections, denominated a "shoulder" connected to the support structure, an "elbow," and a "wrist" supporting the claw. Separate hydraulic cylinders are connected to at least both the elbow and the wrist and are independently controlled to attempt to move the claw supported on the wrist in a substantially horizontal plane. However, accurately controlling the independent cylinders to effect horizontal movement is difficult.